Escalator-brake.



G. JOHN.

ESCALATOR BRAKE. APPLICATION FILED AUG-25, 1913.

Patented Oct. 10, 1916.

2 SHEETS-SHEET I WITNESSES.

6. JOHN.

ESCALATOR BRAKE. APPLIICATTON FILED AUG-25. 19:3.

Patented Oct. 10, 1916.

2 SHEETSSHEET 2.

BY W4 WIT NESSES:

UNITED STATES PATENT OFFICE.

GRIFFITH J OHN, OE YONKERS, NEW YORK, ASSIGNOR TO OTIS ELEVATOR COMPANY, OF JERSEY CITY, NEW JERSEY, A ,COR1 ORATION OF NEW JERSEY.

IESGALATOR-IBRAKE.

To all whom it mag concern: I

Be it known that I, GRIFFITH JOHN, a subject of the King of Great Britain, residing in Yonkers, in the county of Westchester and State of New York, have invented a new and useful Improvement in Escalator- Brakes, of which the following is a specification.

My invention relates to safety brake apparatus' for passenger type of conveyers, commonly called escalators, and more particularly for reversible type of escalators,

and has for one of its objects, the provision of automatically operative means for effecting the retardation of the escalator, when the latter attains .an undue rate of speed.

Another object of the invention is to provide a mechanical safety brake in conjunction with a power unit having abrake assotype of escalator, for the reason that in an escalator operable only in an ascending direction, it is necessary to provide only a non-returnable brake device such as a roller brake or ratchet, so that in case-of a runaway, such as would result in case of the driving mechanism givlng out for example,

- the escalator cannot run down, but for a reversible escalator, which I will say. for example is desceri'din with a heavy load,

and in this instance, if the driving mecha nism gives out, the application of the roller brake or ratchet will cause the escalator to come to a sudden stop, which would cause the passengers to be thrown forward and downward, and might result in a very serious accident, and to this end I provide automatically operative means operable to 0 effect a gradual retardation of the escalator and without danger of injury to the passengers. 7

Referring now to the drawings, Figure 1 shows in elevation, a general arrangement of an escalator, and drivingmechanism, etc., therefor, with my invention applied Specification of Letters Patent.

Application filed' August 25, 1913. Serial No. 786,575.

thereto, also an electrical controlling device therefor, shown in a modified form; Fig. 2 shows 1n detail, an enlarged view of the safety brake apparatus and automatically operative mechanism associated therewith; Flg. 3 shows a plan view of Fig. 2; Fig. 4,

shows in detail a view of a, centrifugal governor, used in conjunction with my invention. The apparatus shown in Fig. 1 compris- 111 the escalator proper, will be described 'on y in general, the details of construction and arrangement of parts being fully shown and described in the patent to C. D. Seeberger, No. 1,025,316, issued May 7, 1912. In Fig. 1, a series of connected steps 1, are

provided with rollers 2, ada ted to travel on tracks 3. Links 4, associated with the steps on the upper run 5 and lower run 5 of the escalator mesh'with sprocket wheels 6, fixed on adriving shaft 7, driven by a motor --8, through a double worm and gear connection 10. An electro-responsive brake apparatus 11, shown diagrammatically is of a well known type, and comprises a brake band 12 normally held applied to a brake pulley 13, by a spring 14, and released therefrom upon magnetization of an electro- -magnet 15. In addition to the latter brake,

I provide an automatically operated differential safety brake 16, which comprises,

brake pulleys 17, which are located at both ends of the driving shaft 7, and are fixed thereon. Associated with each of the brake pulleys are brake levers 18 pivotally supported at 19 by brackets 20, which are suitably secured to framework 21, of the escalator. One of the ends of the brake bands 22, is fixed at a point 23 to the brake levers,

'and the other end at a point 24;, these two points of connection on the lever 18 being such as to obtain a differential and powerful application of the brake bands, with the use of a small weight 43 adjustable on the lever 18. With the brake levers as shown in Fig. 2, the brake bands are released from the brake pulleys, and the levers under normal running conditionsare held in this position by means of trip devices 25 and 25, fixed on a shaft'26. The trip devices are providedwith a latch 27, which engages the ends 28 of their respective levers to keep the brake bands released from their respective pulleys.

A centrifugal governor is fixed on. a 110 a shaft 30 with a sprocket wheel 31, and'any connection, or from the links on the escalator steps as is shown in Fig. 2, which comprises a gear wheel '32, positioned to mesh with the links on the upper run of the escalator, the gear wheel in turn rotating the sprocket wheel 33, which is on a shaft 34 therewith, the sprocket wheels '33 and 31 being connected by a sprocket chain 35. The centrifu gal governor 29 is of a well known ty e and comprises a wheel 36, having a hub 3 and arms 38, radiating therefrom. Weighted centrifugal arms 62 are journaled in the arms 38, and at the other extremity of each of the said weighted arms is engaged a rod 40, connecting it with the opposite weighted arm at a point between the journal and the outer extremity 39, and each of the said rods are provided with springs 41. By this construction it is evident, the centrifugal impulse of each of the weighted arms is communicated to the other to make them act together. The governor is set to operate ata certain predetermined speed and when the arms fly outwardly the bosses 39 thereon strike an arm 42, integral with the trip device 25, thereby knocking the latch 27 on the trip device out of engagement with the end of the brake levers, thereby allowing the brake band to be applied by the action of the weights 43, on the levers. The said weights are adjustable on the levers by means of adjusting bolts 44. Upon operation of the trip device 25 it transmits. motion through the shaft 26 to the .trip device 25, thereby effecting the application of the brake bands on both sides of the escalator simultaneously. An arm 45 integral with the trip device, effects the opening of a double pole knife switch 46, for a purpose hereinafter described.

The operation of the apparatus will now be described.

A direct current source of supply designated and is directed by means of a main line potential switch P, to a controller box R and is directed therefrom in a manner to rotate the motor in a direction to cause the escalator to descend, for example. The potential switch is now closed by hand and is self holding, it having a winding 47 therefor, contacts 48.. and 49, conductor 50, contact 51. contact 52, cond 'ctor 53, contact 54, switch 46, conductor .7, winding 47 to the minus line. The winding of the primary brake electromagnet 15, is as follows: contacts 48 and 49, conductors 50'and 50, contacts 58 and 59, conductor 60, winding of the electromagnet 15, conductor 61, to the minus line. "The primary brake magnet now being energized will lift the brake, and the connected across the mains as follows! motor will now operate to cause the escalator to descend. I will say now for example the escalator is heavily loaded, and the driving the brake bands instantly, and the escalator will be brought to a gradual stop. This operation of the trip device will cause the arm 45 thereon to open the knife switch 46, and thereby open circuit thewinding of the potential switch, the said knife switch being connected in series with the potential switch winding. The potential switch will now open, thereby cutting off the current supply from the motor and primary brake and the latter will operate to retard the motor, which in this instance if allowed to continue its rotation might cause serious damage.

Although I have shown and described my invention applied to a conveyer of the step type together with a particular type of driving mechanism, I do not wish to be limited in the applicationof my invention to this particular type of conveyer or driving mechanism. and it is obvious that those skilled in the art may make various changes in the details of construction and arrangement of parts, without departing from the spirit and A scope of my invention.

What I claim and desire to secure by Letters Patent of the United States is 1. The combination with an electrical power unit having a main brake electrically associated therewith, a source .of electrical power supply, a potential switch controlling circuits to the power unit and said main brake, an auxiliary brake, and governorcontrolled means for controlling the operation of the switch and the auxiliary brake.

2. The combination with an electrical power unit, braking apparatus therefor, comprising a main electrically controlled brake and an auxiliary mechanical brake, a source of electrical power supply, a potential switch for controlling the operation of the power means and electrical brake, and governor-controlled means, operable to effeet the opening of the switch and the application of the brakes simultaneously.

3. In safety apparatus, the combination with a main shaft, a countershaft, electric power means for driving the shafts, a source of electrical power supply, an electrically operated brake for the main shaft, an auxiliary brake for the countershaft, a potential switch for controlling the operation of the power means and electrical brake, a governor operatively connected with one of the potential switch and the application -ernor, operable to effect the opening of the of the auxiliary brake simultaneously.

4. In safety apparatus, the combination with a main shaft, a countershaft, electric power means for driving the shafts, a source of electrical supply, an electrically operated brake for the main shaft, an auxiliary me-' chanical brake for the countershaft, a potential switch for controlling the supply to the power means, an electrical circuit controlled by the potential switch for controlling the operation of the electro-magnetic brake, a governoro one of the said sha ts, and means controlled by the governor comprising a trip and switch, operable simultaneously to effect the opening of the potential switch and application of the auxiliary brake.

5. In safety apparatus, the combination with a main shaft, a countershaft, electric power means for driving the shafts, a source of electrical supply, an electrically operated brake for the main shaft, an auxiliary mechanical brake for the countershaft, a trip device for holding the latter brake released, a centrifugal governor for actuating the trip device, a normally closed switch adapted to be opened by the trip device, a potential switch having a self holding circuit including the last named switch, and a circuit controlled by the potential switch for controlling the operation of the electromagnetic brake.

6. In safety apparatus, the combination with a main and countershafts driven by an electrical power unit a source of electrical supply, an electrically operated brake for the main shaft, an auxlliary mechanical eratively connected with y brake for the countershaft, comprising a and a circuit controlled by the potential I switch for controlling the operation of the electro-magnetic brake.

7. In safety apparatus, the combination with a main and countershafts driven by electrical power means, a source of electrical supply, an electro-magnetic brake associated with the main shaft, an auxiliary brake for the countershaft comprising brake pulleys fixed at both ends thereof, a pair of pivoted levers, a pair of brake bands attached to the levers, a transverse rod, a pair of trip devices keyed to the rod and engaging the levers normally to hold the brake bands released, a centrifugal governor for actuating the trip device, a normally closed switch adapted to be opened by one of the trip devices, a potential switch having a self holding circuit including the said last named switch, and a circuit controlled by the potential switch for controlling the operation of the electromagnetic brake.

In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnessesf I V GRIFFITH JOHN. Witnesses:

WALTER C. STRANG, ERNEST L. GALE,'J r. 

